1. Field of the Invention
The present invention relates to a nozzle testing device and an image forming apparatus.
2. Description of the Related Art
In image forming apparatuses such as inkjet printers that make printing by discharging ink on a recording medium, clogging of a nozzle for discharging ink causes discharge failure to degrade the image quality of a printed image. It is known that a test pattern for testing is formed by discharging ink from the nozzles to a recording medium and the test pattern is used for testing for discharge failure of the nozzles. If discharge failure is detected, maintenance of the nozzles is performed.
For example, Japanese Laid-open Patent Publication No. 2010-23459 discloses a method of detecting discharge failure of nozzles, such as non-discharge of ink and ink droplet flight deflection, by forming a pattern including a solid recording area and a dots area and analyzing the captured image of the pattern. Specifically, according to the method described in Japanese Laid-open Patent Publication No. 2010-23459, when a white line is detected from the solid recording area, whether the discharge failure is caused by non-discharge of ink or ink droplet flight deflection is determined by checking the presence/absence of corresponding dots in the dots area.
Image forming apparatuses are now widespread that make printing using special ink such as colorless transparent ink called clear ink and white ink in addition to yellow, magenta, cyan, black, and other color inks. Ink such as clear ink and white ink have low visibility when discharged on a recording medium. Because of this, when the nozzles that discharge clear ink and white ink are tested for discharge failure, the method described in Japanese Laid-open Patent Publication No. 2010-23459 fails to detect a white line from the image of the solid recording area and fails to appropriately test the nozzles for discharge failure.